Electronic thermometry finds an extensive and steadily increasing application in many fields such as industry, science and medicine. This invention relates to an electronic thermometer which can be used for many applications, even though the specific description concentrates primarily on its clinical use in medical care.
There are a number of features which are desirable for the optimum design of a clinical thermometer. The reading should be unambiguous, the thermometer should be easily reusable from patient to patient without need for sterilization, and an accurate temperature reading should be reached quickly and reliably. The requirement for quick response (of an order of seconds) is quite important since it translates, in a hospital setting, into efficient time utilization by nurses and paramedics.
Many clinical electronic thermometers of today use a thermistor as a temperature sensor. A thermistor has many useful features, such as large temperature coefficient of resistance as well as adequate reproducibility and stability. However, when properly encased, its response time is not much better than that of a conventional thermometer. Typical equilibrium times range from 30 seconds to several minutes. Other measurement schemes have been devised utilizing variations of measurable electrical and magnetic parameters, including capacitance, inductance, or resistance variation with temperature. None have afforded a rapid response time compatible with other requirements set forth above as desirable for clinical application.